1. Field of the Invention
The present invention relates to a downhole tool for oil and gas production. More particularly, the present invention relates to a frac sleeve system. Even more particularly, the present invention relates to a frac sleeve system with unlimited shifting between opened and closed ports without mechanical intervention by a setting tool.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
Frac sleeve systems were developed to replace the slow and expensive process of running individual bridge plugs to isolate segments of a well with multiple stimulation targets along the wellbore. The wellbore runs through multiple zones of productivity within the earth. Bridge plugs and packers are deployed one at a time to isolate the productive zones. The one-by-one installation is not efficient, and a frac sleeve was developed to isolate multiple zones with a single tool.
The frac sleeve has a plurality of ports along the length of the sleeve. The ports are selectively opened or closed depending upon the desired zone. The control of the ports has been performed by a ball dropping through the pipeline. A ball travels through the pipeline to engage a pressure seat of the frac sleeve. A ball of a particular diameter or particular weight will open or close a particular set of ports at the desired depth. The types of balls and pressure seats can be set to control opening and closing of ports along the frac sleeve.
Current frac sleeve systems disclose different structures and methods to control opening and closing of ports, including selectively opening some ports and not others. Differential pressure actuated tools can be activated by a single seat, such that differential pressure across the single seat is used to open different ports at different times. Alternatively, multiple balls with different diameters and weights can fall through the pipeline and activate a respective pressure seat, according to which ball is dropped. Frac sleeve systems have also enabled the same ball to be able to drop through several seats to activate different ports, instead of relying upon multiple balls with different diameters.
Besides controlling which ports are opened, current frac sleeve systems re-close the ports or open another set of ports, after the initial activation. A frac sleeve system has ports in the closed position, while being run-in the borehole to the proper location. Once placed, the frac sleeve system is activated so that a first set of ports is opened. After the frac or production activity is completed, the first set of ports can be closed and/or a second set of ports can be opened for a new frac or production activity. The current frac sleeve systems can proceed to the next activity without removing the spent frac sleeve system and replacing with a new frac sleeve system. For example, a dissolvable ball releases the pressure seat to return the frac sleeve to an original configuration. A ball can also be dislodged from the pressure seat by flow restrictors or differential pressure within the tool. Some pressure seats can also be set to count a number of balls passing through, so as to close the ports after a pre-determined number of balls has passed through the pressure seat. Also, other structures, such as outer and inner sleeves can move relative orientation to each other for a second set of ports to open, while the first set of ports close. A separate shifting tool can also be deployed to re-close the ports or open another set of ports. Other technology in the field of frac sleeve systems affects flow into the frac sleeve from the desired zone, such as flow restricted ports, and a swivel sub for horizontal wellbores.
A frac sleeve system 1 generally includes an outer sleeve 2, an inner sleeve 3, a locking ring 4, a ball seat 5, and a plurality of ports 6 in the inner sleeve 3 as shown in FIGS. 1A and 1B. The frac sleeve system 1 starts in the closed position in FIG. 1A with the locking ring 4 holding the inner sleeve 3 in place relative to the outer sleeve 2. The ports 6 of the inner sleeve are not aligned with openings 7 on the outer sleeve 2, so that there is no fluid flow through the frac sleeve system 1. Once positioned, a ball 8 is dropped through the borehole to engage the ball seat 5. The ball 8 triggers the locking ring 4 to disengage, and the inner sleeve 3 is slidable relative to the outer sleeve 2. The ball 8 or fluid pressure from the surface can increase pressure to break the locking ring 4 to release the inner sleeve 3. The inner sleeve 3 slides into a position of alignment of the ports 6 and openings 7 so that fluid can flow through the frac sleeve system 1. Delivery of fluid through the frac sleeve system 1 can now be accomplished in this open position shown in FIG. 1B. The ball 8 does not always remain in the ball seat 5 in the open position, so that fluid can be delivered more easily.
The prior art frac sleeve system 1 includes various known means to re-close the system 1 to stop the fluid flow. There is no downward originating force available to return the inner sleeve to the locking ring. Fluid pressure is pumped down from the surface, not up from the borehole. The prior art includes dropping a different sized ball to trigger the inner sleeve to slide further down the outer sleeve, while also moving the ports out of alignment with the openings. Alternatively, a spring 9, shown in FIG. 1B, can provide a return force on the inner sleeve back towards the locking ring to again change alignment of the ports and openings. However, the spring 9 would still require another ball and fluid pressure from the surface to compress the spring 9. There is also the limitation that the spring 9 cannot return the inner sleeve to the locking ring. The amount of upward slide of the inner sleeve would be determined by the length of the spring 9 in the un-compressed state. As such, regardless of how the prior art frac sleeve systems are opened and then closed, these prior art systems are not re-useable. The original sequence from closed to opened cannot be replicated without generation of pressure toward the locking ring.
The setting tool is another prior art option to re-close the system 1. Coiled tubing or wireline intervention delivers a tool to the frac sleeve. The tool mechanically closes the open ports, re-setting the frac sleeve for another ball. The intervention requires stoppage time, so that the production ceases for the delivery of the setting tool through the wellbore. There is also the risk of damage to the wellbore, as different tools are lowered each time to re-close the ports.
It is an object of the present invention to provide an embodiment of the frac sleeve system that is reuseable.
It is an object of the present invention to provide an embodiment of the frac sleeve system that can be opened and closed repeatedly.
It is another object of the present invention to provide an embodiment of the frac sleeve system with a reuseable top locking means for a closed position.
It is another object of the present invention to provide an embodiment of the frac sleeve system with a reuseable bottom locking means for an open position.
It is another object of the present invention to provide an embodiment of the frac sleeve system with a reuseable spring means for returning an open configuration to a closed configuration.
It is still another object of the present invention to provide an embodiment of the frac sleeve system with an improved inner sleeve member and outer sleeve or outer housing.
It is still another object of the present invention to provide an embodiment of the frac sleeve system with an inner sleeve member having a guide slot.
It is still another object of the present invention to provide an embodiment of the frac sleeve system with an outer housing having a guide pin engaged with a guide slot of an inner sleeve member.
It is still another object of the present invention to provide an embodiment of the frac sleeve system with a guide slot and guide pin to control the use of pressure to moving between a closed configuration and an open configuration.
It is yet another object of the present invention to provide an embodiment of the frac sleeve system with a reuseable spring means with a torque portion.
It is yet another object of the present invention to provide an embodiment of the frac sleeve system with a reuseable spring means to provide a twisting force to the inner sleeve.
These and other objectives and advantages of the present invention will become apparent from a reading of the attached specifications and appended claims.